Unit of DFT energy calculation

Gets Around

4:56:27 AM PDT - Thu, May 22nd 2014
hi. I am trying to calculate energy of hydrogen bond, based on bond length, using b3lyp xc and aug-cc-pvdz basis set. All I am getting as my DFT energy is like(for bond length 2.5 angstrom): Total DFT energy = -75.580432010766 One electron energy = -105.872820803882 Coulomb energy = 37.948128899715 Exchange-Corr. energy = -8.772184258729 Nuclear repulsion energy = 1.116444152131 Numeric. integr. density = 8.999998951783 Total iterative time = 1.6s Now I am not being able to find out that what actually is the unit of Total DFT energy and all other parameters.

Forum Regular

11:54:24 AM PDT - Thu, May 22nd 2014
Hi Neo, All energies in the ab-initio capabilities are reported in Hartree (or equivalently atomic units) unless stated otherwise. See for example http://www.ucl.ac.uk/~uccaati/Energy.html for conversion factors. Huub

Gets Around

11:23:35 PM PDT - Thu, May 22nd 2014
hello. start oh-dat echo geometry noautoz units angstrom symmetry c1 o -1.874 24.116 62.689 h 0.878 22.906 65.000 end basis * library aug-cc-pvdz end dft odft mult 4 xc b3lyp end task dft energy i am using this above code to calculate.. but if the output DFT energy is in Hartees then sure there must be a serious error in my code. Because no way hydrogen bond be that strong as 75 Hartee or 47100kcal/mol. Any comment regarding this issue would be very helpful. thank you.

Just Got Here

8:20:17 AM PDT - Thu, Jun 5th 2014
basically you're not generating the bond energy here, well you are but you also have the energy to put the electrons in all of the other orbitals (the various non bonding orbitals) the best way to get a bond energy is probably to do a scan along the bond and see how the energy changes, it should generate a bond dissossiation curve which you can then use to judge what the bond energy is

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